1. Field
The presently disclosed subject matter relates to strobe lighting units having a xenon light source, and more particularly to strobe light units with a simple structure including a detecting circuit that can reliably detect degradations of the xenon light source, and which can also detect a non-lighting of xenon discharge tube in the xenon light source in confidence.
2. Description of the Related Art
Into devices having a shooting with camera such as a smart phone, a mobile phone, a digital camera, etc. a strobe light unit having a flash light such as a xenon light source is generally incorporated. In such the devices, when the flash light degrades due to temporal charge of an electrode, a discharge gas and the like or when the flash light becomes non-functional in the worst case, a favorable picture should not be taken by using the shooting with camera of the devices.
Hence, strobe light units including a detecting circuit that can detect a degradation of strobe light have been developed. A conventional detecting circuit of the degradation of strobe light, for example, is disclosed in Patent document No. 1 (Japanese Patent Application Laid Open JPH07-159232). FIG. 7 is a block diagram showing a conventional detecting circuit of the degradation of strobe light, which is disclosed in Patent document No. 1.
The conventional detecting circuit of the degradation of strobe light includes: a strobe light 51; a power supply 57 configured to light the strobe light 51; a trigger circuit configured to output a lighting signal to the power supply 57 so as to be able to flash the strobe light 51; a photo detector 52 receiving a flash light emitted from the strobe light 51; an integrator 53 configured to detect an amount of the light received by the photo detector 52; an AD converter 54 converting analog data of the amount of the light into digital data; a measurement circuit 55 measuring whether the amount of the light is normal or not; and an indicator 55 displaying said result output from the measurement circuit 55.
However, when the strobe light 51 degrades in the conventional detecting circuit, the detecting circuit may have a question, which has potential of missing a certain detection of the degradation of the strobe light 51 due to variations of the amount of the flash light emitted from the strobe light 51. Especially, when the strobe light 51 includes a plurality of xenon discharge tubes and when the amount of the flash light emitted from the strobe light 51 decreases because of a degradation of only one xenon discharge tube, the conventional detecting circuit may have another question, which has potential of missing a certain detection of the degradation of the strobe light 51 due to a variation of an amount of flash lights emitted from other xenon discharge tubes, which normally operate.
In addition, the conventional detecting circuit needs the photo detector 52 to receive the flash light emitted from the strobe light 51, and therefore may be subject to a complex structure because a space is required to incorporate the photo detector 52 into the devices having a shooting with camera such as a smart phone, a mobile phone, a digital camera, and the like and because the devices are small size. Moreover, the conventional detecting circuit may decrease a detecting accuracy of the degradation of the strobe light 51 due to a slightly misalignment of the photo detector 52.
The above-referenced Patent document and additional Patent documents are listed below and are hereby incorporated with their English abstracts in their entireties.    1. Patent document No. 1: Japanese Patent Application Laid Open JP H07-159232    2. Patent document No. 2: Japanese Patent Application Laid Open JP2010-014782    3. Patent document No. 3: Japanese Patent Application Laid Open JP2009-053320    4. Patent document No. 4: Japanese Patent Application Laid Open JP2007-109551
The disclosed subject matter has been devised to consider the above and other problems, characteristics and features. Thus, an embodiment of the disclosed subject matter can include a strobe light unit using a xenon light source with a simple structure that can detect a degradation of the xenon light source without a photo detector. In this case, the strobe light unit can light the xenon light source with a simple structure, and also can detect degradations including a non-lighting of the xenon light source without a photo detector. Thus, the strobe light unit can result in an increase in the possible range of devices having the shooting with camera, and therefore can be employed for various devices including a thin mobile phone, a thin smart phone, etc.